Gene Munster, an analyst with Piper Jaffray, predicts the new iPad will sell for $299, have a screen between 7 and 8 inches (down from 9.8 inches for the full-size iPad) and be available in a Wi-Fi only version. Other iPads have Wi-Fi and cellular service plans available.

The new iPad comes at a time when many companies are dramatically increasing their portfolio of smaller tablets to try and take on Apple. Amazon just unleashed several new Kindle tablets including a beefed up $199 Kindle Fire; Google and Samsung have the $199 Nexus 7. Both have 7-inch screens.

Microsoft will launch its answer to the iPad, Surface, at a splashy event in New York on October 26th. No price has been announced for the Surface, which has a larger screen.

By not having a 7-inch model, "Apple is ceding 20% of the market to competitors," says Munster.

Apple in the past has insisted that consumers prefer the large screen of its iPad, but now, says Munster, "There are some people who just naturally prefer having a smaller tablet," and Apple can satisfy them.

Munster projects that Apple will sell 5-10 million of the smaller iPads by the end of the year, depending on whether it can get its production issues in order. "If things so smoothly, it's 10 million, if things don't go well, it's 5 million," he says.

The new iPhone5, which burst out of the gate three weeks ago with sales of 5 million phones, has been plagued by supply issues. Apple could sell way more phones if it had them, Munster says.

Apple puts its next-day supply available as pre-orders online only, at 10 p.m. ET. Munster checked every night last week at 100 stores, and all were sold out quickly. "There wasn't a store anywhere where a phone was available after 11 p.m."

Apple introduced a new iPad in March, the successor to the iPad 2, with a brighter, sharper screen and an improved video camera. Nearly 75 million iPads have sold since the tablet was first introduced in 2010. Apple has sold nearly 250 million iPhones.